The acid zinc electroplating bath and process of the present invention is particularly applicable but not necessarily limited to so-called high speed zinc electroplating operations over a wide current density range such as encountered in strip plating, wire plating, rod plating, or the like. Electro-deposited zinc of a semi-bright to a lustrous appearance is desirable in such instances to provide a decorative plating while simultaneously imparting corrosion protection to the article.
Acid-type zinc electroplating baths heretofore known have incorporated brightening agents or combinations thereof which have not provided adequate versatility in their use over a broad range of current densities and have been deficient in providing the requisite semi-bright or lustrous zinc deposit under high speed electroplating conditions. Such prior art plating baths have also been expensive to use and require careful control.
Many of the problems and disadvantages associated with prior art acid zinc electroplating baths are overcome in accordance with the present invention by employing a controlled effective amount of a mixture of primary and secondary brightening agents which are effective to produce a semi-bright to lustrous zinc deposit over a broad range of current densities and which composition is particularly applicable for high speed electroplating processes.